Health

Consequences of direct genetic testing for germline mutations in the clinical management of families with multiple endocrine neoplasia, type II

Article Abstract:

DNA analysis appears to identify people at risk for developing an inherited cancer syndrome called multiple endocrine neoplasia, type II (MEN-II). MEN-II is associated with early tumor onset. Researchers studied affected and unaffected members in 10 families that met the clinical criteria for MEN-II. Genetic testing showed germline mutations in the RET proto-oncogene in 8 affected families. Two families without RET mutations had a mutation in the VHL gene, which causes von Hippel-Lindau disease. Those suspected of having the syndrome should be screened for the RET mutation and VHL syndrome. Unlike biochemical tests, the RET mutation analysis does not require retesting if the test is negative. The test is reliable in patients of all ages.

Different subtypes of multiple endocrine neoplasia type 2 (MEN-2) appear to be linked to specific gene mutations in the RET oncogene. MEN-2 is characterized by tumors in various glands, including the thyroid and adrenals. It has three subtypes depending on the organs affected by tumors: MEN-2A, MEN-2B and familial medullary thyroid cancer (FMTC). Researchers performed genetic testing on 477 families worldwide who had a family history of MEN-2. A gene mutation at position 634 in the RET oncogene was associated with MEN-2A, while a mutation at position 918 was specific for MEN-2B and mutations at 768 and 804 were specific for FMTC.

Mutations in the RET proto-oncogene appear to be responsible for multiple endocrine neoplasia type 2 (MEN-2) and Hirschsprung's disease. The RET proto-oncogene is located on chromosome 10q11.2 and appears to code for a receptor tyrosine kinase. Mutations in the gene have been found in 92% of families with MEN-2, which would allow the development of a genetic test for this disease. MEN-2 is characterized by cancer of the thyroid and other endocrine tumors. RET mutations have also been found in 10% to 40% of patients with Hirschsprung's disease, which is characterized by intestinal obstruction.